What were the competitive scene like in the previous generations and this generation?

From what I've heard, Gen 1 is Alakazam day in and night out.

Gen 2 was stall wars.

Gen 3... I don't know.

Gen 4 was Garchomp, stealth rock and sturdy/focus sash only.

Gen 5 was weather and firepower wars.

What is gen 6 like?

Pic kind of unrelated